Foundations - supporting structures of buildings and structures

 

The foundation (latin. Fundamentum ) is a building supporting structure, a part of a building, a structure, which perceives all the loads from the overlying structures and distributes them along the base. As a rule, they are made of concrete, stone or wood.

Foundations, as a rule, are laid below the depth of soil freezing, in order to prevent their bulging. On non-rocky soils, shallow foundations are used in the construction of light wooden structures (the foundation is above the ground freezing level). This type of foundation is suitable mainly for small garden houses, summer baths and outbuildings.

Foundation under the foundation

 

Geological rocks occurring in the upper layers of the earth's crust used for construction purposes are called soils. Soils are clusters of particles (grains) of various sizes, between which there are pores (voids). Soils that directly absorb loads from a building or structure are called bases. The bases are artificial or natural.

Natural grounds are divided: rocky and non-rocky.

Rocky soils - volcanic, metamorphic and igneous rocks with a rigid connection between the grains of minerals (granites, sandstones, basalts, limestone) are the most solid foundations of buildings and structures. Water-soluble and softened rock in water includes gypsum, anhydrite, shale, and some types of sandstone.

Coarse soils, uncemented rocky soils, can be a solid foundation. They are divided into rubble, dusvyanye.

Depending on the size of the sand particles are divided into gravel, large, medium size, small and dusty. Depending on the density of addition or porosity, sandy soils are dense, medium density and loose. Depending on the degree of humidity or the degree of filling of the volume with water, sandy soils are distinguished as slightly moist, moist and saturated with water. Oils are wetted fine-grained and silty sands with clay impurities (not suitable for construction).

Clay soils are cohesive soils with dimensions of flat particles, bonded by internal cohesion forces. They are plastic. The clay soils include loams and sandy loams containing sand impurities. Depending on the degree of humidity or the degree of filling of the pores with water, soils are low moisture, wet and saturated with water. Soils in a water-saturated state become fluid and are called fluids.

Bulk soil - artificial mounds, formed as a result of cultural and industrial activities of man. The depth of the foundation from the ground level on clay soils should, as a rule, be 15-20 cm below the depth of winter frost penetration.

Groundwater - formed as a result of precipitation entering the soil.

Soils that have ice in their composition are called frozen . The freezing of some soils can cause them to swell.

Soil studies

The work of the soil under load is as follows. Under the action of the load from the foundations in the subgrade, pressure arises, the value of which depends on the own weight of the soil and on the weight of the building or structure. The pressure of the soil's own weight, depending, in turn, on the bulk weight of the soil and on the depth of the foundation, is called natural (domestic) pressure. The pressure from the weight of a building or structure is called additional pressure.

 

Artificial bases

 

Artificial bases are 2 types :

- bases created by compaction;

- the grounds created by the fortification.

The soils of the bases are compacted by surface tamping with heavy tampers in the form of a truncated cone weighing 1.5–3 tons, lifted by a crane to a height of 3–4 m and dropped on a sealing surface. This method used in the compaction of bulk and subsiding soils, is called surface. Deep compaction produced "ground piles" - driving core in the form of a wooden conical piles. When the soil is weak, they are often replaced with sand pads. Sand is laid in layers with a thickness of 150 - 200 mm and compacted rammers or surface vibrators with watering water.

The thermal method of strengthening the soil consists in forcing the soil into the thickness of a soil under pressure through pipes of air heated to 600 ° - 800 ° C, or in burning combustible products fed into a hermetically sealed well under pressure. Burnt soil acquires the properties of a ceramic body, does not get wet and does not swell.

Cementation of soils is carried out by injection into the soil through cement suspension pipes, cement - clay solutions, which are blocked in it.

Silicatization consists of injecting liquid glass and calcium chloride solutions through pipes into the ground and is used to strengthen sandy silt soils, silts and macroporous soils. The injection is made to a depth of 15-20 m and more, and the spreading radius of silicification reaches 1 m.

Samples of soils and wells penetrated by drilling, or from pits (a pit is a small geological mine, a pit) are sections (columns) and geological profiles of the layers of the soil massif in characteristic directions.

Foundations

 

Requirements for foundations:

1) strength;

2) stability, overturning and sliding in the plane of the base of the foundation;

3) resistance to aggressive groundwater;

4) resistance to atmospheric factors (frost resistance; swelling of soils during freezing);

5) compliance with the durability of the service life of the building;

6) industrialism;

7) cost effectiveness.

According to the design scheme, the foundations are divided into: tape, columnar or free-standing, solid and pile (see. Fig. 7).

The cost of foundations of the total value of the building is: with a baseless solution of 8-10%; with a basement of 12-15%, and the complexity is 10-15%.

Strip foundations

 

Monolithic strip foundations (Fig. 9.).

In the simplest case - rectangular. In most cases, to transfer pressure to the base, not exceeding the standard pressure on the ground, it is necessary to broaden the base of the foundation (Figure 10).

The depth of foundation should correspond to the depth of the layer of soil that can be taken as a natural base.

It is also necessary to take into account the depth of soil freezing. Regulatory frostbite depth is specified in SniPe.

For heaving soils, the depth of foundation should be considered to be 100 mm lower than the freezing depth.

In non-rocky soils, the depth of foundation is independent of the depth of frost penetration.

Foundations of rubble stone do not meet the requirements of industrial construction (mechanization of work is difficult, the pace of construction is reduced, especially in winter).

The use of concrete and concrete foundations allow a wider use of mechanization during their construction.

 

Prefabricated strip foundations : (Fig. 11.)

For external walls 400, 500, 600mm;

The height of the foundation block is 580 mm;

Block seam - 20 mm

From one depth of the monolithic strip foundation to another, they gradually move with the device of ledges.

The ratio of the height of the ledge to its length should be no more than 1: 2, and the height of the ledge should be no more than 0.5 m, and the length - not less than 1 m. On stronger soils, the ratio of the height of the ledge to its length is allowed no more than 1: 1, and the height of the ledge is not more than 1 m.

If the building is erected on precast foundations, the height of the ledge can be taken equal to the height of the unified unit, i.e. 0.6m; in this case, the length of the ledge must be at least 1.2 m.

The distance between the axes of the seams is 600 mm (in height).

The blocks are stacked with bandaging sutures in a staggered manner. Length - 1180 mm; 2380 mm (dogs) additional thickness - 180 mm. Foundation blocks with seams with a reinforced concrete mortar, on reinforced concrete pads with a height of 300 mm and width up to 2.80 m (Fig. 12).

 

Intermittent foundations for bearing walls (Fig. 8-b).

Monolithic reinforced concrete belts in areas with high seismicity. Reinforcing bars + concrete pouring 5-6 cm.

Fragments of monolithic areas: at the corners in the locations of communications.

 

Tape panel foundations (Fig.14.).

In large-panel buildings, separate blocks of foundations and basement walls should be replaced with large-sized elements. They consist of endless frameless trusses (panels and blocks or ribbed panels - pillows).

 

Pillar foundations (fig. 15, 16, 17.).

When the pressure on the ground is less than the standard, strip foundations should be replaced columnar. Foundation pillars (concrete or reinforced concrete) overlap reinforced concrete beams on which walls are built. To eliminate the bulging of the foundation beam when heaving the soil, a pillow of sand or slag 0.5 m thick is arranged under it.

 

Solid foundations (Fig. 13.).

With weak or non-uniform soils, as well as with very large loads on the columns in order to avoid uneven precipitation, the foundations unite the (ribbed) reinforced concrete slab system.

With solid foundations, a uniform draft is ensured, which is especially important for frame-panel and large-panel buildings of high number of storeys. In addition, it is well protected basements from the penetration of groundwater at high levels, when the basement floor is exposed to the bottom of a large hydrostatic pressure.

 

Pile foundations .

They are used when the achievement of a natural base is economically or technically impossible due to the large depth of its foundation with significant loads, as well as in other cases.

Distinguish piles stand (based on the thickness of the soil), trailing piles, which are held in a weak soil due to its compaction and transfer the load on the soil by friction that occurs between the pile and the soil (Fig. 18).

Depending on the method of immersion in the ground apply zabivnye, ramming, bored, piles, shells, and bush and screw piles.

Drop-in reinforced concrete and wooden piles are immersed by using pile drivers, vibratory pile drivers and vibration pressing units.

Reinforced concrete piles can be made whole and composite (from separate sections).

Wooden driving piles are arranged where there are constant temperature and humidity conditions (Fig. 19, 20, 21, 22, 23, 24, 25.).

Rammed piles are arranged by filling in a concrete or other mixture of pre-drilled, punched or stamped wells. The lower part of the wells can be widened by explosions (piles with camouflage heel).

Drilled piles are distinguished from ramming by the fact that finished reinforced concrete piles are installed in the well with the gap between the pile and the well filled with a sand-cement mortar (Fig. 20).

At the upper ends of the piles or on special widening of the upper ends (top ends) stack "beams or slabs - grillage. They are used prefabricated (reinforced concrete) or monolithic. Recently, constructive solutions have been developed for pile foundations" without grillages (Fig.23, 25).

In terms of piles may consist of single piles - under the supports; piles of ribbons - under walls in one or more rows; pile bushes; solid pile field - for heavy structures (Fig. 20, 21, 22).

 

Protection of buildings against groundwater

 

To protect the walls of baseless buildings from capillary moisture in all walls, horizontal waterproofing is installed in the basement of 2 layers of roofing material, roofing material or a layer of fat cement mortar of 1: 2 with a thickness of 20-30 mm 150-200 mm below the floor of the first floor and 150 200 mm above the pavement mark or blind area.

Foundations that are in an aggressive environment (in the presence of aggressive compositions in the groundwater) are made of concrete on pozzolanic portland cement and slag Portland cement, except in cases of alkaline activity, when any type of cement can be used, except for pozzolanic and slag Portland cement.

At the pressure of water from 0.1 to 0.2 m to protect the basement from water penetration under the basement floor lay a layer of soft oily clay with a thickness of 250 mm and concrete preparation with a thickness of 100-200 mm. The outer surface of the walls is insulated with plaster cement mortar, followed by coating with hot bitumen for 2 times and clogging with a layer of soft oily clay with a thickness of 200-250 mm (Fig. 26).

When the pressure of water from 0.2 to 0.8 m, there is a danger of floating up the floor, so the floor is artificially weighted. In these cases, a concrete pad 100-150 mm thick is laid on the ground, the surface of which is leveled with a cement mortar or asphalt layer 20-25 mm thick followed by a sticker on a bituminous or asphalt mastic of a waterproofing carpet of 2 or 3 layers of roofing material, waterproofing, brizola . To protect this part of the waterproofing carpet from mechanical damage, arrange a protective wall with a thickness of 120 mm of well-baked bricks, laid out on the cement mortar.

At high water pressures, when the groundwater level exceeds the basement floor level by more than 0.8 m, the floor is arranged in the form of a flat reinforced concrete slab loaded with house walls, or in the form of a slab with ribs top.

On a flat reinforced concrete slab, (and when ribbed - in the gaps between the ribs), heavy concrete is laid, on which a clean floor is arranged.

The effectiveness of a particular type of foundation depends on the volume, cost, labor intensity and consumption of materials.

Pile foundations are more economical than tape ones by 32-34% in terms of cost, by 40% in terms of concrete costs and by 80% in terms of the volume of earthworks. Such savings can reduce the cost began to increase - 1 - 3 kg per 1 m2.

 

 

Foundations	Volume foundation	Labor intensity	Cost of	Steel consumption	Consumption cement
Rubble	100	100	100	0	100
Concrete	52	58	68	100	120
Precast Concrete (solid)	52	55	85	100	150
Precast Concrete hollow	40	53	75	100	115

 

STRIP CONSTRUCTIONS

From solid wall foundation blocks	Of hollow blocks	Option with the device basement.	Monolithic foundation
On a sandy pillow	Rubble foundation with brick cladding		Concrete foundation

1- base plate; 2 - foundation block; 3 - wall block;

4 - solid concrete
CONSTRUCTIONS OF COLUMN BASE
 

BUT	B	1-1
And - A design on a base pillow; B - The design of the foundation stakannogo type. 1 - outer base panel; 2 - pyramidal base of the column; 3 - foundation beam; 4 - foundation glass.

Fig. 7

 

 

TAPE BASES FOR CONVENTIONAL CONDITIONS

 

a - modular solid; b - precast intermittent; in - monolithic; g - monolithic with detached columns; d - assembled - monolithic

Fig. eight.

GENERAL OVERVIEW OF THE FOUNDATION OF THE FOUNDATIONS UNDER THE EXTERNAL AND INTERNAL WALL

FOUNDATIONS IN BUILDINGS WITH BASEMENT CELLS FOR EXTERNAL WALLS FOR INTERNAL WALLS

FOUNDATIONS IN BUILDINGS WITHOUT A CELLAR FOR EXTERNAL WALLS UNDER INTERNAL WALLS

 

Fig. 9.

 

TAPE MONOLITH BASES OF BRICK AND BULK BUILDINGS THE FOUNDATION PLAN

GENERAL TYPE OF CONSTRUCTION OF FOUNDATIONS UNDER EXTERNAL AND INTERNAL WALL

NON-PASSAGE UNDERWATER CHANNELS UNDER FLOORING ON SOIL

SECTIONS OF FOUNDATIONS (AT THE GROUND WATER LEVEL BELOW THE FLOOR OF THE CELLAR)

 

WATERPROOFING OF CELLARS WITH GROUND WATER PRESSURE UP TO 0.2 m;

1m AND MORE ABOUT THE FLOOR BASEMENT

 

Fig. ten.

REINFORCED CONCRETE BASE PILLOWS AND CONCRETE BLOCKS	FOUNDATION PLAN
	1,3 - pillow block with pre-stressed reinforcement; 2 - shortened wall block; 4 - shortened base pillow 5 - wall foundation block
DESIGN COMPLETE FOUNDATIONS	A - cross construction; B, C - options for the device solid base plate; G - box construction foundations.

Fig. eleven.
REINFORCED CONCRETE PLATES AND BLOCKS FOR BELT FOUNDATIONS BY SERIES 1.112-1, ISSUE 1 AND 2

	SECTION		LENGTHS mm	MARKS	SKETCHES	NOTES
	Width mm	High, mm
PLATES	3200 2800 2400 2000 1600 1400 1200 1000 800 600	500	1180; 780	F32; F32-8 F28; Ф28-8 F24; F34-8 F20; F20-8		Slabs are molded from concrete grade 150; 200, reinforced with steel mesh, located at the sole. Grids with a seam of the working reinforcement 100; 150 (● Ø 6 + 9) and mounting 250; 150 (● Ø 4,5) are made of rods of a periodic profile by resistance spot welding. * В марку плит с усиленным армированием добавляется индекс «У», например Ф16У. Чертежи плит содержатся во 2-ом выпуске серии 1.112 -1.
		300	2380; 1180; 780	Ф16;Ф16-12;Ф16-8 Ф14;Ф14-12;Ф16-8 Ф12;Ф12-12;Ф12-8 Ф10;Ф10-12;Ф10-8
			2380; 1180	Ф8; Ф8-12 Ф6; Ф6-12
БЛОКИ СПЛОШНЫЕ	600 500 400 300 600 500 400	580	2380; 880	ФБС6; ФБС6-9 ФБС5; ФБС5-9 ФБС4; ФБС4-9 ФБС3; ФБС3-9		Блоки формуются из бетона марки 100, усиленные – из бетона марки 200. В марку усиленных блоков добавляется индекс «У», например ФБС6-У
		280	1180	ФБСН-6 ФБСН-5 ФБСН-4

ЛЕНТОЧНЫЕ БЛОЧНЫЕ ФУНДАМЕНТЫ КИРПИЧНЫХ КРУПНОБЛОЧНЫХ ЗДАНИЙ

ПЛАН ПОДОШВЫ ФУНДАМЕНТА	ОБЩИЙ ВИД НАРУЖНОЙ СТЕНЫ
ПЛАН СТЕН ТЕХНИЧЕСКОГО ПОДПОЛЬЯ (ПОДВАЛА)	SECTIONS OF FOUNDATIONS (AT THE GROUND WATER LEVEL BELOW THE FLOOR OF THE CELLAR)

Fig.12.

PLATE FOUNDATION UNDER THE BUILDING OF INCREASED FLOOR DESIGN OF THE FOUNDATION
OF 14-FLOOR BUILDING WITH BRICK WALLS
 

 

 

 

 

 

 

TYPES OF HOLES

GENERAL VIEW OF THE BASE ON THE LONGITUDINAL WALL

PLAN OF CONSTRUCTION NETWORK PLATE BASES

 

 

 

Fig. 13.

BASIS OF PANEL BUILDINGS - TAPE TILES

 

PLANNING OF THE FOUNDATION AND WALLS OF THE TECHNICAL UNDERGROUND

 

GENERAL KIND OF CONNECTION OF WALLS

SECTIONS OF FOUNDATIONS (AT THE GROUND WATER LEVEL BELOW THE FLOOR OF THE CELLAR)

DETAILS OF CONNECTION OF THE SUB-BOUNDED PANELS

Fig. 14.

FOUNDATION OF FRAME BUILDINGS

AND SEPARATELY STANDING FOUNDATIONS

 

 

and - the plan of the base of the frame building; b - building plan on separate foundations; in - resting the wall on the column base; M - W - bearing plinths on prefabricated shoes.

Fig. 15.

COLUMN FOUNDATIONS

 

 

 

 

1 - foundation, 2 - basement panel,

3 - bolt, 4 - wall panel,

5 - column, 6 - flooring

COLUMN FOUNDATIONS OF LOW-RISE BUILDINGS

 

FOUNDATION PLAN

 

INCISION

1-1

 

 

1 - pillar; 2 - randbalka; 3 - wall;

Fig. sixteen.

 

 

COLUMN CONCRETE FOUNDATIONS

UNDER BUILDING WITH A RELATED FRAME (SERIES AI - 04)

 

MARKING PLAN FRAGMENT

 

 

Fig. 17

MONOLITHIC BASE

 

 

PILED FOUNDATIONS

 

A - piles of the rack, B - C - piles hanging

 

Fig. 18.

PRIZMATIC REINFORCED CONCRETE PLAINS PILES OF CONTINUOUS SECTION

ROUND HOLLOW PILOTS-SHELLS

WHOLE AND COMPOSITE

WITH ROUND CAVITY

 

 

PIECE SHEAR DETAILS

BOLT JOINT WITH A TOTAL LENGTH OF PILED UP TO 48 M

FOUNDATIONS OF BRICK AND BULK BUILDINGS

PILED FOUNDATIONS WITH MONOLITHIC REINFORCED CONCRETE ROOM

 

PILOT FIELD PLAN

AND MONOLITH ROUGHTERS

GENERAL VIEW OF THE FOUNDATIONS IN THE END OF THE BUILDING

 

 

 

Fig. nineteen.

PILED FOUNDATIONS

CUTS

1-1 2-2

 

Strong ground. Weak ground.

 

 

Weak ground

 

 

 

PORTS TYPES

1 2 3 4 5 6 7 8 9

10 11

 

1-4 - concrete and reinforced concrete piles are square, round, solid, hollow; 5-6 - stuffed usual and with a wide heel; 7-8 - camouflage; 9 - with hinged open. stops; 10 - prismatic; 11 - pile in the leader well

Fig. 20.

CONSTRUCTIONS OF PILED FOUNDATIONS

 

 

CONSTRUCTION OF THE TEAM OF A TEAM OF HEADING UNDER A SINGLE FOLD

SINGLE ORDER PILET LOCATION

CHILDREN POSITION PILES

DOUBLE ROW PILED LOCATION

SCRAP PAY UNDER A SINGLE COLUMN

 

 

 

1 - pile; 2 - modular cap; 3 - monolithic reinforced concrete grillage;

4 - reinforced concrete grillage under the column

Fig. 21.

 

PILED NON-SPRING FOUNDATION PILABLE FOUNDATION WITHOUT ROLLERS AND HEADS

 

1 - pile; 2 - tip; 3 - basement panel; 4 - overlap; 5 - column; 6 - bolt

Fig. 25

THE BASES OF PANEL BUILDINGS ON SHORT ITS SILETS WITH REINFORCED CONCRETE PANEL

 

PLANE OF FIELD SECTION OF FOUNDATIONS

PLAN FOR LAYOUT OF ROLLERS, BASE BEAMS AND SOCKET PANELS

GENERAL VIEW AND DETAILS OF THE FOUNDATION UNDER THE MEDIUM PART OF THE BUILDING

 

 

CLOSING PLAN

OVER THE TECHNICAL UNDERGROUND

Fig. 22

PIECES OF PILED FOUNDATIONS

 

and - at the decision of a socle from blocks; b - the same, from prefabricated panels;

in - junctions of the precast grillage

Fig. 23.

 

BASES OF PANEL BUILDINGS ON PILES WITH HEATINGS AND REINFORCED CONCRETE RAILWAYS

PLAN OF LAYOUT OF BULOK ROSVERK

AND PELT FIELDS

STRIPED BEAM STRETCHING WITH ROUNDING AT THE DEFORMATION SEAM

SECTION OF FOUNDATIONS

CONNECTION OF BEAMS A ROLLER WITH A HEADING

GENERAL VIEW OF THE FOUNDATION IN THE MIDDLE OF THE BUILDING

 

Fig. 24

WATERPROOFING FOUNDATIONS

 

WITH GROUND WATER PRESSURE NOT MORE THAN 200 mm WITH GROUND WATER WASTE 200-1000 mm

 

 

 

WITH GROUND WATER PRESSURE OVER 1000 mm

 

 

1 - roll waterproofing; 2 - painting waterproofing; 3 - waterproofing waterproofing; 4 - brick protective wall; 5 - fiberglass;

6 - expansion joint; 7 - clay; 8 - basement floor; 9 - screed;

10 - reinforced concrete slab; 11 - concrete loading layer;

12 - preparation

 

Fig. 26